Date Range:

Wednesday, July 10, 2002 to Saturday, August 5, 2006

Publication Date:

Sunday, December 12, 2004

Methods:

Plot location was chosen based on dominate vegetation type (T or W). The tussock tundra plots are located near the Moist Acidic Tundra plots characterized by Shaver and Chapin (1991). The wet sedge plots are located near the outlet of Toolik Lake; all plots have been used by the Arctic LTER project at Toolik Lake.

In wet sedge tundra, three 1 m2-sized plots were positioned randomly in each of two treatments of block 2 of the LTER wet sedge scheme (outlet site), control and N+P-fertilized , respectively, in 2000. Paired control and fertilized plots were labelled with 14C and 15N at one of three different dates of the summer season 2001.

In moist acidic tussock tundra six 1 m2 sized plots were positioned in three of the "X" (=extra") blocks of the LTER scheme, in 2001, inside an area extending 5 m from the boardwalks and, positioning plots so that similar area shares between tussocks and intertussock areas was achieved. In each of the three X blocks two 1m2-sized plots were established. The whole 5 m area of the X blocks extending from the board walks was divided into two halfs, each containing one of the 1m2 sized plots. One half was set aside as the control and the other half was designated to be fertilized. Fertilization with a Hoagland solution (see protocol) started in late summer 2001, and was repeated annually after that , early in the summer season. Paired control and fertilized plots were labelled with 14C and 15N of the summer season 2002; all three pairs were labelled as closely together in time as logistically possible.

Sampling description:
Destructive harvests of plant (aboveground and belowground tissues) and soil material were carried out in the year of, and in the years following, 14C and 15N labelling.

In wet sedge tundra (labelled in 2001) harvests were carried out in the summers of 2001, 2002, 2003, and 2005.
In tussock tundra (labelled in 2002) harvests were carried out in the summers of 2002, 2003, 2004, and 2006.

After seperation, material was dried in forced-air ovens at 55 dec C, subsequently ground, and analyzed for 14C. We used a R.J Harvey OX-500 Biological Oxidizer to combust the samples. The resultant CO2 was bubbled into a 14C scint cocktail and ran on a Beckman Coulter Scintilation Counter.

This material is based upon work supported by the National Science Foundation under Grants #DEB-1637459, 1026843, 9810222, 9211775, 8702328; #OPP-9911278, 9911681, 9732281, 9615411, 9615563, 9615942, 9615949, 9400722, 9415411, 9318529; #BSR 9019055, 8806635, 8507493. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.